1. Field of the Invention
The present invention relates to an apparatus for the automatic playing of a piano, specifically, an apparatus that plays music on demand by using prerecorded play information, which is held in a storage device, to control a keyboard and pedals.
Apparatuses for automatic playing that are attached to, for example, acoustic pianos are in current, practical use. To produce music, these apparatuses use prerecorded play information to operate drive mechanisms that manipulate keyboards and pedals.
Such an apparatus also incorporates a means to adjust the volume of the music produced so that it is suitable for the performance location and the social ambiance.
2. Description of the Related Art
A conventional apparatus for automatic playing of a piano incorporates a storage device, e.g., a floppy disk, that holds play information, including, for example, key numbers, key depression force and time information. When the apparatus receives a signal to begin playing, via, for example, an operation panel, it reads play information from the storage device and uses this information in its operation of the keyboard and pedals of a piano.
More specifically, play information constituting event information groups is previously stored in a storage device. As shown by the example in FIG. 6, one event information group consists of an identification symbol, a key number, key depression force, and time information.
When playing is initiated, one event information group of the play information is read from the storage device, and the included time information is examined. When the time information corresponds to an execution timing (time) for the read-out event information, procedures for this event are performed, i.e., keys are depressed or released.
The execution time for an event information group is determined as follows: A time count, which is held by a time counter that counts clock cycles, is compared with the time information in the read-out event information group, and when they correspond it is assumed that the procedures for the event should be performed.
After the procedures for one event information group have been completed, the next event information group is read from the storage device and the described process is repeated. Music is produced by repeatedly reading and processing event information groups.
Dynamic automatic playing is controlled as follows: The average electric power is determined based on information that dictates how strongly, or at what key depression force, keys (key numbers) designated in play information should be depressed, and solenoids are driven using the determined electric power. Keys and pedals coupled to these solenoids are therefore manipulated (depressed or released) at a strength (velocity) relative to the average electric power, and predetermined dynamic music is played.
Volume control methods commonly used for conventional apparatuses for automatic playing of pianos are as follows:
With one method where a volume is designated through operation of a volume control, to increase volume the automatic playing apparatus adds a predetermined value, which agrees with a control value selected via the volume control, to the key depression force included in play information; and to reduce volume the apparatus subtracts a predetermined value, which agrees with a control value selected via the volume control, from the key depression force in the play information. In this manner, a conventional apparatus prepares the key depression force information that is supplied to a solenoid driver.
This method supplies a selected voltage, determined in consonance with control values designated via the volume control, to activate solenoids to operate a keyboard and pedals, and absolutely increases or decreases key depression force.
Using this method, while the absolute volume is raised or reduced, the range of the volume, i.e., the dynamic range, is not changed. This is because, as shown in a graph in FIG. 4, a conversion characteristic, which is represented by broken lines, occupies parallel positions as it is shifted up or down. When the volume is changed in this manner, discordant sounds are produced, especially when the volume is lowered.
In another common volume control method, which is depicted in FIG. 7, data for different conversion characteristics are stored in multiple conversion tables 50.sub.1 to 50.sub.n. When a specific volume is designated via a volume control, one of the conversion tables 50.sub.1 to 50.sub.n is selected by a switch 51; and, from the data in the selected conversion table, information about key depression force that is to be sent to the solenoids is obtained.
With this method, by setting the contents of a conversion table to a desired value, it is possible not only to control absolute volume but also to control the dynamic reproduction range of music. As its memory size depends on the number of conversion tables, however, this method requires too large a memory.
The first volume control method described above, the method that, in consonance with the operation of a volume control, effects an absolute volume modification of reproduced music but does not affect the reach of soft and strong sounds, i.e., the dynamic range, is not desirable because tonal quality, especially when a lower volume is designated, is not tempered, and reproduced music, when the dynamic range is too wide for the selected volume, is inharmonious.
The other method described above, whereby, in consonance with the operation of a volume control, volume is controlled by the selection of one of a multiple of conversion tables, is also not desirable because it requires too large a memory.